Russell’s mammoth impact in the fields of mathematical logic, philosophy, and mathematical foundations lends interest to his Introduction to Mathematical Philosophy (now more than ninety years old), a minimally technical book which addresses the logical foundations of mathematics. The book affords an opportunity, limited but still significant, to ponder arguments and observations of historical import.

Russell remarks that the book deals “with a body of knowledge which, to those who accept it, appears to invalidate much traditional philosophy, and even a great deal of what is current in the present day. In this way, as well as by its bearing on still unsolved problems, mathematical logic is relevant to philosophy.” (pp. v–vi) In this, and in a few other comments of a similar bent, Russell gingerly places the content of this book within philosophy. The fit may well have seemed awkward at the time.

Russell held that mathematics can proceed in two directions, one toward increasing complexity.

The other direction, which is less familiar, proceeds, by analysing, to greater and greater abstraction and logical simplicity; instead of asking what can be defined and deduced from what is assumed to begin with, we ask instead what more general ideas and principles can be found, in terms of which what was our starting-point can be defined or deduced. It is the fact of pursuing this opposite direction that characterizes mathematical philosophy as opposed to ordinary mathematics. (p. 1)

Russell’s pursuit (which I will not get into) involves laying a foundation for mathematics in logic. No philosopher is clearer than Russell and this book is no exception. Having taken this bow to Russell, I find that the informal treatment of the subject makes for sometimes tedious reading. Today, a treatment of the same material using standard notation would likely be far more compact. In fairness to Russell, a good part of his intended readership consisted (as he observed) of philosophers with little ability in symbolic reasoning for whom an informal treatment was necessary.

Russell’s ideas have generated an enormous amount of fruitful research. Even so, in reading the book, one might ask: has philosophy’s concentration on Russell’s pursuit (and similar pursuits) led to philosophy’s missing anything of substance about mathematics? If so, what? (David Corfield’s Towards a Philosophy of Real Mathematics is relevant here.)